[SOLVED] Plugin name disappear in PluginLoader...

Hi guys, I have found some strangeness inside QPluginLoader, When I set up the name of plugin, after set up, it does not handle the name...
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QPluginLoader config;
config.setFileName(QString("Project.Configuration"));

Please read the manual carefully, then you can get the answer.
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fileName : QString
This property holds the file name of the plugin.
To be loadable, the file's suffix must be a valid suffix for a loadable library in accordance with the platform, e.g. .so on Unix, .dylib on Mac OS X, and .dll on Windows. The suffix can be verified with QLibrary::isLibrary().
If the file name does not exist, it will not be set. This property will then contain an empty string.
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